Evolution of computer-aided tomography (CT) systems is categorized in terms of “generations.” For example, a third generation CT system includes one or more energy integrating detector(s) mounted at one side of a rotating gantry. One or more x-ray source(s) are mounted at an opposite side of the rotating gantry. The gantry rotates around a patient as the x-ray source emits x-rays, which are detected by the energy integrating detectors after passing through the patient. This detected energy is collected as view data and processed into CT images.
A fourth generation CT system includes photon-counting detectors arranged along a circle or portion of a circle (arc) that is centered on the patient. The photon counting detectors are fixed and do not rotate around the patient. Instead, a rotating x-ray source, which rotates about the patient, emits x-rays which are detected by the photon counting detectors in order to acquire view data that is then processed to form a CT image.